IntroductiontoParticlePhysics andCosmology · Total Delivered: 48.1 pb1 Total Recorded: 45.0 pb1...

Introduction to Particle Physics

and Cosmology

V. Kartvelishvili

Georgian Teachers’ Programme

CERN, 13 November 2017

Georgian Teachers, 13 Nov 2017 (page 1) V. Kartvelishvili (Lancaster U)

Outline

Brief Introduction

The Standard Model (SM)

CERN and its accelerator structure

Antimatter studies

Large Hadron Collider (LHC)

Proton-proton collisions, luminosity and triggers

Lepton pair production: J/ψ,Υ, Z, . . .

Other SM measurements: tt, W±, ZZ, . . .

Observation of the Higgs Boson

Links with Cosmology

Dark matter and dark energy

Unanswered questions in particle physics and in cosmology

Summary and outlook


From http://teachers.web.cern.ch/teachers/archiv/HST2002/webgroup/mcclean/Introduction to Particle Physics.ppt


Fundamental constituents of the Standard Model


Particle Physics — What’s This About?

‘Elementary’ Particles — e, p, n, ν, µ, τ, γ,W,Z . . . and their interactions.

You should already know a few things about them.

Is Particle Physics a difficult subject?

Compared to other areas of physics (nuclear, solid state, bio-. . . ) and other sciences(botany, chemistry, zoology, medicine) PP is actually very simple:

Particles have (relatively) few properties (‘quantum numbers’).

These properties usually have few discrete values.

Particles obey very simple, relatively few, well-defined laws.

All elementary particles of the same type are absolutely identical.


Why does PP Seem So Hard Then?

The world of particles is so far from our everyday experience, that all these simpleproperties and simple laws may look and seem unnatural and weird;

What can we do?

‘Friendly’ names: strangeness, charm, colour, top, bottom. . . Find analogies andsimple rules

Many mathematical methods used to describe the world of particles are quiteadvanced (Group Theory, Quantum Field Theory, Advanced Statistics . . . )

What can we do?

Use simplified maths, skip derivations. . .

Your intuition fails to work

What can we do?

Build our intuition by solving lots of various problems


What’s the Scale?

‘Elementary’ Particles:

the smallest constituents

of matter (known so far):

leptons and quarks, and also

the interaction carriers:

photons γ, gluons g,

W± and Z0 bosons.

Well-established models and theories at present exclude gravitational interactions:

1. quantum theory of gravity has not been built yet;

2. may (should!) be tied to properties of space-time at tiny scales;

3. too weak to matter for particles under ‘usual’ circumstances.

However, weak, electromagnetic and strong interactions are understood anddescribed reasonably well.


Is SI System Useful in Particle Physics?

Main properties of particles: mass m, charge e, spin s.

For an electron in SI system:

me = 9.109× 10−31 kg

e = −1.602× 10−19 C

sz = ±h/2 = ±(1/2)× 1.055× 10−34 J · s

Particle physicists do not use SI system. Instead, a particle physicist would write:

me = 0.51 MeV/c2

e = −1 proton charge

sz = ±1/2

The last equation suggests: in particle physics

h = 1.055× 10−34 J · s = 1

which, for one thing, states that in particle physics the product of units of [energy] and[time] is dimensionless.


Can we Make it Even Simpler?

So, it’s natural to choose units such that h = 1. This means that

[energy] × [time] =1 and also [momentum] × [distance] =1

Now, remember the relativistic relation between Energy E, momentum p and mass m:

E2 = p2 c2 +m2 c4

Relativistic particles move with speeds close to speed of light. Carrying all these hugefactors like (300000000 m/s)2 around will be avoided in a system of units where c = 1,which simply means that [new unit of time] is [old unit of time]/c.

The choice h = 1 and c = 1 would mean that

Energy, momentum and mass are measured in the same units

Angular momentum is dimensionless

Time and distance are measured in the same units

Energy is inverse of time

One needs just one dimesional unit, which is usually chosen as the unit of energy

In Particle Physics this is 1 GeVGeorgian Teachers, 13 Nov 2017 (page 9) V. Kartvelishvili (Lancaster U)

Natural System of Units

The system of units with h = 1 and c = 1 is called the Natural system:

1 unit of length = 1 GeV−1

≃ 0.1978 fm

1 unit of time = 1 GeV−1

≃ 0.6588 · 10−24s

1 unit of energy = 1 GeV

1 unit of momentum = 1 GeV sometimes GeV/c

1 unit of mass = 1 GeV sometimes GeV/c2

Note: 1 GeV = 1000 MeV and (1 GeV)−1 = (1000 MeV)−1, but 1000 GeV−1 = 1 MeV−1

One more unit: barn b for cross section: 1 b = 10−24 cm2.

One barn is far too big a unit for particle physics:

1 b = 103mb = 10

6 µb = 109nb = 10

12pb = 10

15fb

The cross sections of most interesting processes in particle physics are usually measured infemtobarns fb.

Rare processes have smaller cross sections, and vice-versa.


Generations and masses

Three “generations”

Getting heavier and heavier

Top quark especially heavy

No clue why. . .


CERN ‘overview’

Birdseye view of CERN

and neighbourhood

Alps, lake Geneva,

Geneva airport

LHC ring shown as

the red line


CERN accelerator complex

A very long chain of accelerators, culminating

in the Large Hadron Collider (LHC)

Producing beams of protons, ions,

antiprotons. . . even neutrinos!

Lots of experiments, all very interesting

and important

I will only cover very few. . .


Antimatter studies

Theory predicts a very special exact symmetry

between particles and antiparticles.

Properties of antihydrogen – a bound state of an

antiproton and a positron – are predicted to follow

strictly the same pattern as ‘normal’ hydrogen.

A number of CERN experiments, feeding from Antiproton Decelerator (AD) are designed tomake precise measurements of various properties of antimatter particles.

The problem is that if an antiproton or a positron

touches with normal matter, they annihilate.

Special, very sophisticated devices – magnetic traps –

are used to keep antiprotons and positrons long enough

to allow antihydrogen to form and to be studied...


ATRAP, ASACUSA, ALPHA. . .

ASACUSA compares matter and antimatter using

atoms of antiprotonic helium and antihydrogen,

studies properties of matter-antimatter collisions

In ALPHA, antihydrogen is synthesized and trapped for

long enough to study hyperfine splitting in the atomic

atomic spectra of antihydrogen

No deviation from theory expectations has been

observed so far...


The Large Hadron Collider (LHC)

LHC is the flagship

of CERN research

programme, colliding

two proton beams with

energy of 13 TeV

One of the largest and

most complicated

engineering constructions

in human history

Two multi-purpose experiments: ATLAS and CMS

Others – such as LHCb and ALICE – are more specialised


LHC tunnel, ATLAS and CMS

Tunnel 27 km long

100 m under the surface

2000 magnets of various types

Two huge multi-purpose experimental

installations: ATLAS and CMS


Is LHC really a proton - proton collider?

High energy of constituents is

needed to produce something new

and interesting

A proton is a bunch of quarks and gluons, each carrying a fraction of energy

13 TeV of pp collision energy barely enough to produce a 2 TeV object. . .


Quark and gluon distributions in a proton

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

x

x f

(x)

Only 30% of proton energy

is carried by the three

constituent uud quarks

Most of proton energy is

carried by gluons

The “sea” of quark-antiquark

pairs is also important

M2 = x1 × x2 × (13 TeV )2

dσ ∼ f1(x1)× f2(x2)× σ(M2)


Cross sections and units

The intensity of various collisions is measured in terms of the cross section forparticular reactions

Cross section is the effective area which needs to be crossed by a test particle toget scattered

Since early days of nuclear physics, measured in barns

1 barn = 10−28 m2 = 100 fm2

is about the size of lead or uranium nucleus

Total cross section of proton-proton collisions is about 100 millibarn at 7 TeV

Interesting processes like Higgs production have much smaller probabilities, andhence much smaller cross sections, measured in picobarns (10−12 barn) orfemtobarns (10−15 barn) or even attobarns (10−18 barn)

The smaller the cross section of a process, the fewer events you get

Integrated luminosity of 100 pb−1 means that if the cross section is 1 pb, you willsee 100 events


Luminosity

Day in 2011

28/02 30/04 30/06 30/08 31/10

/da

y]

1In

teg

rate

d L

um

ino

sity [

pb

0

20

40

60

80

100

120

140

160

180 = 7 TeVs ATLAS Online Luminosity

LHC Delivered

ATLAS Recorded

In early days of LHC:

100’s of collisions / sec

Now:

many millions / sec

No time for viewing

events one-by one. . .

Full computing power of CERN only allows to reconstruct “just” a few hundred eventsper second

Very careful selection (“triggering”) of potentially interesting events is required!


1974: discovery of J/ψ

⇐ Discovery 1: Ting’s group

pN → e+e−X

at Plab = 30 GeV/c

[Aubert et al., PRL, 6/11/1974]

Found a peak in e+e− inv.mass at 3.1 GeV, called it J .

Discovery 2: Richter’s group ⇒

(a) e+e− → hadrons

(b) e+e− → µ+µ−

(c) e+e− → e+e−

[Augustin et al., PRL, 7/11/1974]

Found a peak in all these three cross-sections,

at the c.m.s. energy 3.1 GeV; called it ψ.

Now we know: J/ψ is a bound state of charm-anticharm, cc.Georgian Teachers, 13 Nov 2017 (page 22) V. Kartvelishvili (Lancaster U)

History of 20th century Particle Physics in one plot

[GeV]µµm

1 10 210

En

trie

s /

50

Me

V

210

310

410

510

610

710Trigger

EF_2mu4_DiMu

EF_2mu4_Jpsimumu

EF_2mu4_Bmumu

EF_2mu4_Upsimumu

EF_mu4mu6_Jpsimumu

EF_mu4mu6_Bmumu

EF_mu4mu6_Upsimumu

EF_mu20

Z

ρ/ω φ

ψJ/

(2S)ψ(1S)Υ

(2S)Υ(3S)Υ

1 L dt ~ 2.3 fb∫ = 7 TeV s

ATLAS Preliminary


pp → J/ψ(→ µ+µ−) +X


pp → J/ψ(→ e+e−) +X


Proper Decay Time of the J/ψ vertex

Pseudoproper Time [ps]2 0 2 4 6 8 10

Eve

nts

/ [

0.0

73

ps ]

10

210

310

410

7 TeV data

Combined fit

Signal component

Background component

1 = 35 pbintL

ATLAS Preliminary

Pseudoproper Time [ps]2 0 2 4 6 8 10

Pu

lls /

[ 0

.07

3 p

s ]

2

1

0

1

2


Fraction of non-promptly produced J/ψ

[GeV]T

ψJ/p

1 10

pro

du

ctio

n f

ractio

nψ

No

np

rom

pt

J/

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

ATLAS

|<0.75ψJ/

|y=7 TeV,sATLAS

|<1.2ψJ/

|y=7 TeV,sCMS

|<0.6ψJ/

|y=1.96 TeV,sCDF

Spinalignment envelope

1L dt ~ 2.3 pb∫


pT dependence of prompt J/ψ

[GeV]T

ψJ/p

0 5 10 15 20 25 30

dy [

nb

/Ge

V]

T/d

pp

rom

pt

σ2

)d µ+ µ

→ψ

Br(

J/ 3

10

210

110

1

10

210

310

|<2.0ψJ/

|y<ATLAS 1.5

Spinalignment envelope

Colour Evaporation Model

NLO Colour Singlet

NNLO* Colour Singlet

ATLAS

Prompt crosssection

1L dt = 2.2 pb∫= 7 TeVs


bb bound states: Υ system

) [GeV]µµInv. M(

8 9 10 11 12

Events

/ (

0.1

GeV

)

0

5

10

310×

) [GeV]µµInv. M(

8 9 10 11 12

Events

/ (

0.1

GeV

)

0

5

10

310×

ATLAS Preliminary

1 L dt ~ 41.0 pb∫ = 7 TeV s

Data 2010 : Opposite Sign

Fit Projection

Fit Projection of Background

Barrel + Barrel

200 (stat.)±) = 16300 1S

ΥN(

200 (stat.)±) = 4800 2S

ΥN(

100 (stat.)±) = 2300 3S

ΥN(


Spectroscopy of bb mesons

Inva

ria

nt

ma

ss [

Ge

V]

9.2

9.4

9.6

9.8

10

10.2

10.4

10.6

ATLAS

1Observed bottomonium radiative decays in ATLAS, L = 4.4 fb

BB threshold_

Potential model

Worldaverages

Worldaverages

(1S)ϒ

(2S)ϒ

(3S)ϒ

(4S)ϒ

(1P)bJ

χ

(2P)bJ

χ

(3P)bJ

χ

Mass barycentre

Mass barycentre

Mass barycentre

(Hatched: calorimetry)

(Filled: conversions)

= PC

J L =

10

++(0,1,2) 1

Spectroscopy similar to hydrogen atom

Υ(1S): ground state

Υ(2S, 3S): radial excitations

Three families of χb:

orbital excitations, L = 1

Until 22 December 2011, only

χb(1P ) and χb(2P ) were observed


All three χb peaks as seen by ATLAS

[GeV]S)k(ϒ

) + mµ+µ) m(γµ+µm(

9.6 9.8 10.0 10.2 10.4 10.6 10.8

Ca

nd

ida

tes /

(2

5 M

eV

)γ µ

+ µ

0

20

40

60

80

100

120

140

160

180

200

220ATLAS γ(1S)ϒFit to

γ(2S)ϒFit to

γ(1S)ϒBackground to

γ(2S)ϒBackground to

γ(1S)ϒData:

γ(2S)ϒData:

Converted Photons

1Ldt = 4.4 fb∫


Event with χb(3P ) candidate


Integrated luminosity in 2010, 2012, 2016

Day in 2010

24/03 19/05 14/07 08/09 03/11

]1

Tota

l In

tegra

ted L

um

inosity [pb

0

10

20

30

40

50

60

Day in 2010

24/03 19/05 14/07 08/09 03/11

]1

Tota

l In

tegra

ted L

um

inosity [pb

0

10

20

30

40

50

60 = 7 TeVs ATLAS Online Luminosity

LHC Delivered

ATLAS Recorded

1Total Delivered: 48.1 pb1

Total Recorded: 45.0 pb

Day in 2012

01/04 28/05 25/07 21/09 18/11

]1

To

tal In

tegra

ted L

um

inosity [fb

0

5

10

15

20

25

= 8 TeVs ATLAS Online Luminosity

LHC Delivered

ATLAS Recorded

1Total Delivered: 21.4 fb1Total Recorded: 20.0 fb

Look at the scales on y-axes: 1 fb−1 = 1000 pb−1

Dramatic progress over the years, meaning that one can now access less and lessfrequent processes...

...and at a higher and higher energy!


Z → µ+µ− candidate at high luminosity

There are 20+ collisions

in one bunch crossing,

with a Z → µ+µ− candidate

produced in one of them.


W+W− pair production

W+→ µ+νµ

W−→ e−νe

Neutrinos escape

detection

⇒ missing PT


Standard Model cross sections vs theory


Top quark mass measurement


Decay modes of the Standard Model Higgs Boson

[GeV]HM100 200 300 400 500 1000

Hig

gs B

R +

Tota

l U

ncert

310

210

110

1

LH

C H

IGG

S X

S W

G 2

011

bb

ττ

cc

ttgg

γγ γZ

WW

ZZ


Higgs(-like object) observation

[GeV]4lm80 100 120 140 160

Events

/2.5

GeV

0

5

10

15

20

25

30

1Ldt = 4.6 fb∫ = 7 TeV: s1Ldt = 20.7 fb∫ = 8 TeV: s

4l→(*)ZZ→H

Data(*)

Background ZZ

tBackground Z+jets, t

=125 GeV)H

Signal (m

Syst.Unc.

Preliminary ATLAS

100 110 120 130 140 150 160

Eve

nts

/ 2

Ge

V

2000

4000

6000

8000

10000

ATLAS Preliminary

γγ→H

1Ldt = 4.8 fb∫ = 7 TeV, s

1Ldt = 20.7 fb∫ = 8 TeV, s

Selected diphoton sample

Data 2011+2012=126.8 GeV)

HSig+Bkg Fit (m

Bkg (4th order polynomial)

[GeV]γγm100 110 120 130 140 150 160E

vents

F

itte

d b

kg

200

100

0

100

200

300

400

500


Higgs decay Branching Ratios vs SM


Questions to the Standard Model

There are three types of interactions in the Standard Model, and the variety of gaugebosons, the interaction carriers: γ for electromagnetic,W±, Z0 for weak, g for strong.

Why are these three types so different – and the fourth, gravity, even more so?

Why are there three generations of quarks and leptons?

Why fractional electric charges of quarks?

Why are the fermion masses so different?

What determines the mixing of various generations?

These and many more questions cannot be answered within SM.

We need a bigger theory. . .


Cosmology: source of inspiration

Universe is made up of ∼ 1011 galaxies; each galaxy contains 1010 − 1012 stars

Cosmology: science about the history of the Universe

Assumption: laws of physics have not changed along the way

Method 1: observe the Universe evolution NOW and try to extrapolate backward

Method 2: assume some starting point (the Big Bang) and extrapolate forward

The overall established picture in modern cosmology is arguably as stable and solidas the Standard Model in Particle Physics, but it also has its unanswered questions

The hope (from both camps) is that the answers may be shared!


Glashow’s serpent

As usual, ”natural” system of units:

h = 1, c = 1, kB = 1

distance ∼ time

Energy ∼ 1/distance

Temperature ∼ Energy

Hence, Planck’s mass

Mp =√

hcGN

= 1019 GeV



Expanding Universe

Experimental fact: Universe is expanding

Light from distant galaxies is red-shifted (Doppler effect)

The larger the distance, the more the shift (can be measured precisely)

The light wave expands with space, hence the shift towards lower frequency

Hubble constant: 70 km/s per Megaparsec

Once, the Universe was 3000 times smaller – and 3000 times hotter than today

Cosmic Microwave Background 2.7 K today: photons wandering in space since then

Almost isotropic (same in all directions) – but NOT EXACTLY!


CMB anisotropy

Ripples from times 300 000 years ago, at the level of 10−3

These small non-uniformities may be signals from the seeds of galaxy formation


Polarisation fluctuations

Possible signs of gravitational waves from the Big Bang?


Bariogenesis

Once the Universe was a billion times smaller and hotter than today

Light chemical elements were formed: He4, D, He3, Li, . . .

Relative abundance of these elements can be predicted by theory

Depends on density of matter and number of types of particles

Does not seem to be enough to stop expansion, or even to form the galaxies like ours:


Cosmological inflation

Basic idea: very early, about maybe 10−35 s after the Big Bang, the expansion wasexponentially fast

Can explain why the universe

looks almost flat now

Fate of the Universe

depends on this:


Energy density budget of the Universe

There is some critical value of the energy density which keeps the balance betweenexpansion and contraction of the universe.

Ω = 1 corresponds to

a flat universe – close

to what we see today

Latest measurements show

that there are different

components to this density:


Evidence for Dark Matter – I


Evidence for Dark Matter – II


Experimental data on components of Ω


Unresolved questions in Cosmology

The hope is that Particle Physics can help answer at least some of these!


Beyond the Standard Model

Is there a bigger symmetry group, which will become visible at higher energies?

⇒ Grand Unification

Or maybe the Poincare-Lorentz invariance group can be extended to includeanticummutation relations?

⇒ Supersymmetry

Or maybe our space-time has more than 3+1 dimensions, some of which are“compactified” ?

⇒ Large extra dimensions

These, and many other, theories exist — and predict some observable effects.

Physicists are searching for them, in a hope to answer some of the questions. . .


Supersymmetry searches: lower limits

Model e, µ, τ, γ Jets Emiss

T

∫L dt[fb−1

] Mass limit Reference

Inclu

siv

eS

ea

rch

es

3rd

ge

n.

gm

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en

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rks

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MSUGRA/CMSSM 0 2-6 jets Yes 20.3 m(q)=m(g) 1405.78751.7 TeVq, g

MSUGRA/CMSSM 1 e, µ 3-6 jets Yes 20.3 any m(q) ATLAS-CONF-2013-0621.2 TeVg

MSUGRA/CMSSM 0 7-10 jets Yes 20.3 any m(q) 1308.18411.1 TeVg

qq, q→qχ01 0 2-6 jets Yes 20.3 m(χ

01)=0 GeV, m(1st gen. q)=m(2nd gen. q) 1405.7875850 GeVq

gg, g→qqχ01 0 2-6 jets Yes 20.3 m(χ

01)=0 GeV 1405.78751.33 TeVg

gg, g→qqχ±1→qqW±χ

01

1 e, µ 3-6 jets Yes 20.3 m(χ01)<200 GeV, m(χ

±)=0.5(m(χ

01)+m(g)) ATLAS-CONF-2013-0621.18 TeVg

gg, g→qq(ℓℓ/ℓν/νν)χ01

2 e, µ 0-3 jets - 20.3 m(χ01)=0 GeV ATLAS-CONF-2013-0891.12 TeVg

GMSB (ℓ NLSP) 2 e, µ 2-4 jets Yes 4.7 tanβ<15 1208.46881.24 TeVg

GMSB (ℓ NLSP) 1-2 τ + 0-1 ℓ 0-2 jets Yes 20.3 tanβ >20 1407.06031.6 TeVg

GGM (bino NLSP) 2 γ - Yes 20.3 m(χ01)>50 GeV ATLAS-CONF-2014-0011.28 TeVg

GGM (wino NLSP) 1 e, µ + γ - Yes 4.8 m(χ01)>50 GeV ATLAS-CONF-2012-144619 GeVg

GGM (higgsino-bino NLSP) γ 1 b Yes 4.8 m(χ01)>220 GeV 1211.1167900 GeVg

GGM (higgsino NLSP) 2 e, µ (Z) 0-3 jets Yes 5.8 m(NLSP)>200 GeV ATLAS-CONF-2012-152690 GeVg

Gravitino LSP 0 mono-jet Yes 10.5 m(G)>10−4 eV ATLAS-CONF-2012-147645 GeVF1/2 scale

g→bbχ01 0 3 b Yes 20.1 m(χ

01)<400 GeV 1407.06001.25 TeVg

g→ttχ01 0 7-10 jets Yes 20.3 m(χ

01) <350 GeV 1308.18411.1 TeVg

g→ttχ01

0-1 e, µ 3 b Yes 20.1 m(χ01)<400 GeV 1407.06001.34 TeVg

g→btχ+

1 0-1 e, µ 3 b Yes 20.1 m(χ01)<300 GeV 1407.06001.3 TeVg

b1b1, b1→bχ01 0 2 b Yes 20.1 m(χ

01)<90 GeV 1308.2631100-620 GeVb1

b1b1, b1→tχ±1 2 e, µ (SS) 0-3 b Yes 20.3 m(χ

±1 )=2 m(χ

01) 1404.2500275-440 GeVb1

t1 t1(light), t1→bχ±1 1-2 e, µ 1-2 b Yes 4.7 m(χ

01)=55 GeV 1208.4305, 1209.2102110-167 GeVt1

t1 t1(light), t1→Wbχ01

2 e, µ 0-2 jets Yes 20.3 m(χ01) =m(t1)-m(W)-50 GeV, m(t1)<<m(χ

±1 ) 1403.4853130-210 GeVt1

t1 t1(medium), t1→tχ01

2 e, µ 2 jets Yes 20.3 m(χ01)=1 GeV 1403.4853215-530 GeVt1

t1 t1(medium), t1→bχ±1 0 2 b Yes 20.1 m(χ

01)<200 GeV, m(χ

±1 )-m(χ

01)=5 GeV 1308.2631150-580 GeVt1

t1 t1(heavy), t1→tχ01

1 e, µ 1 b Yes 20 m(χ01)=0 GeV 1407.0583210-640 GeVt1

t1 t1(heavy), t1→tχ01 0 2 b Yes 20.1 m(χ

01)=0 GeV 1406.1122260-640 GeVt1

t1 t1, t1→cχ01 0 mono-jet/c-tag Yes 20.3 m(t1)-m(χ

01 )<85 GeV 1407.060890-240 GeVt1

t1 t1(natural GMSB) 2 e, µ (Z) 1 b Yes 20.3 m(χ01)>150 GeV 1403.5222150-580 GeVt1

t2 t2, t2→t1 + Z 3 e, µ (Z) 1 b Yes 20.3 m(χ01)<200 GeV 1403.5222290-600 GeVt2

ℓL,R ℓL,R, ℓ→ℓχ01

2 e, µ 0 Yes 20.3 m(χ01)=0 GeV 1403.529490-325 GeVℓ

χ+1χ−

1 , χ+

1→ℓν(ℓν) 2 e, µ 0 Yes 20.3 m(χ01)=0 GeV, m(ℓ, ν)=0.5(m(χ

±1 )+m(χ

01)) 1403.5294140-465 GeVχ±

1

χ+1χ−

1 , χ+

1→τν(τν) 2 τ - Yes 20.3 m(χ01)=0 GeV, m(τ, ν)=0.5(m(χ

±1 )+m(χ

01)) 1407.0350100-350 GeVχ±

1

χ±1χ0

2→ℓLνℓLℓ(νν), ℓνℓLℓ(νν) 3 e, µ 0 Yes 20.3 m(χ±1 )=m(χ

02), m(χ

01)=0, m(ℓ, ν)=0.5(m(χ

±1 )+m(χ

01)) 1402.7029700 GeVχ±

1, χ

0

2

χ±1χ0

2→Wχ01Zχ

01

2-3 e, µ 0 Yes 20.3 m(χ±1 )=m(χ

02), m(χ

01)=0, sleptons decoupled 1403.5294, 1402.7029420 GeVχ±

1 ,χ0

2

χ±1χ0

2→Wχ01h χ

01

1 e, µ 2 b Yes 20.3 m(χ±1 )=m(χ

02), m(χ

01)=0, sleptons decoupled ATLAS-CONF-2013-093285 GeVχ±

1, χ

0

2

χ02χ0

3, χ02,3 →ℓRℓ 4 e, µ 0 Yes 20.3 m(χ

02)=m(χ

03), m(χ

01)=0, m(ℓ, ν)=0.5(m(χ

02)+m(χ

01)) 1405.5086620 GeVχ0

2,3

Direct χ+

1χ−

1 prod., long-lived χ±1 Disapp. trk 1 jet Yes 20.3 m(χ

±1 )-m(χ

01)=160 MeV, τ(χ

±1 )=0.2 ns ATLAS-CONF-2013-069270 GeVχ±

1

Stable, stopped g R-hadron 0 1-5 jets Yes 27.9 m(χ01)=100 GeV, 10 µs<τ(g)<1000 s 1310.6584832 GeVg

GMSB, stable τ, χ01→τ(e, µ)+τ(e, µ) 1-2 µ - - 15.9 10<tanβ<50 ATLAS-CONF-2013-058475 GeVχ0

1

GMSB, χ01→γG, long-lived χ

01

2 γ - Yes 4.7 0.4<τ(χ01)<2 ns 1304.6310230 GeVχ0

1

qq, χ01→qqµ (RPV) 1 µ, displ. vtx - - 20.3 1.5 <cτ<156 mm, BR(µ)=1, m(χ

01)=108 GeV ATLAS-CONF-2013-0921.0 TeVq

LFV pp→ντ + X, ντ→e + µ 2 e, µ - - 4.6 λ′311

=0.10, λ132=0.05 1212.12721.61 TeVντ

LFV pp→ντ + X, ντ→e(µ) + τ 1 e, µ + τ - - 4.6 λ′311

=0.10, λ1(2)33=0.05 1212.12721.1 TeVντ

Bilinear RPV CMSSM 2 e, µ (SS) 0-3 b Yes 20.3 m(q)=m(g), cτLS P<1 mm 1404.25001.35 TeVq, g

χ+1χ−

1 , χ+

1→Wχ01, χ

01→eeνµ, eµνe 4 e, µ - Yes 20.3 m(χ

01)>0.2×m(χ

±1 ), λ121,0 1405.5086750 GeVχ±

1

χ+1χ−

1 , χ+

1→Wχ01, χ

01→ττνe, eτντ 3 e, µ + τ - Yes 20.3 m(χ

01)>0.2×m(χ

±1 ), λ133,0 1405.5086450 GeVχ±

1

g→qqq 0 6-7 jets - 20.3 BR(t)=BR(b)=BR(c)=0% ATLAS-CONF-2013-091916 GeVg

g→t1t, t1→bs 2 e, µ (SS) 0-3 b Yes 20.3 1404.250850 GeVg

Scalar gluon pair, sgluon→qq 0 4 jets - 4.6 incl. limit from 1110.2693 1210.4826100-287 GeVsgluon

Scalar gluon pair, sgluon→tt 2 e, µ (SS) 2 b Yes 14.3 ATLAS-CONF-2013-051350-800 GeVsgluon

WIMP interaction (D5, Dirac χ) 0 mono-jet Yes 10.5 m(χ)<80 GeV, limit of<687 GeV for D8 ATLAS-CONF-2012-147704 GeVM* scale

Mass scale [TeV]10−1 1√

s = 7 TeV

full data

√s = 8 TeV

partial data

√s = 8 TeV

full data

ATLAS SUSY Searches* - 95% CL Lower LimitsStatus: ICHEP 2014

ATLAS Preliminary√

s = 7, 8 TeV

*Only a selection of the available mass limits on new states or phenomena is shown. All limits quoted are observed minus 1σ theoretical signal cross section uncertainty.


Exotics searches: lower limits

Mass scale [TeV]

110 1 10 210

Oth

er

Excit.

ferm

.N

ew

quark

sL

QV

’C

IE

xtr

a d

ime

nsio

ns

Magnetic monopoles (DY prod.) : highly ionizing tracks

Multicharged particles (DY prod.) : highly ionizing tracksjjmColor octet scalar : dijet resonance, ll

m), µµll)=1) : SS ee (→L

±± (DY prod., BR(HL

±±H

Zlm (type III seesaw) : Zl resonance, ±

Heavy lepton N

Major. neutr. (LRSM, no mixing) : 2lep + jetsWZ

mll), νTechnihadrons (LSTC) : WZ resonance (lµµee/mTechnihadrons (LSTC) : dilepton, γl

m resonance, γExcited leptons : lWt

mExcited b quark : Wt resonance, jjmExcited quarks : dijet resonance,

jetγmjet resonance, γExcited quarks :

qνlmVectorlike quark : CC, Ht+X→Vectorlike quark : TT

,missTE SS dilepton + jets + →4th generation : b’b’

WbWb→ generation : t’t’th

4

jjντjj, ττ=1) : kin. vars. in βScalar LQ pair (

jjνµjj, µµ=1) : kin. vars. in βScalar LQ pair (jjν=1) : kin. vars. in eejj, eβScalar LQ pair (tb

m tb, LRSM) : → (RW’tq

m=1) : R

tq, g→W’ (µT,e/mW’ (SSM) : tt

m l+jets, → tZ’ (leptophobic topcolor) : tττmZ’ (SSM) : µµee/mZ’ (SSM) :

,missTEuutt CI : SS dilepton + jets + ll

m, µµqqll CI : ee &

)jj

m(χqqqq contact interaction : )jjm(

χQuantum black hole : dijet, F

TpΣ=3) : leptons + jets,

DM /

THMADD BH (

ch. part.N=3) : SS dimuon, DM /THMADD BH (tt

m l+jets, → t (BR=0.925) : tt t→KK

RS glljjmBulk RS : ZZ resonance, νlν,lTmRS1 : WW resonance, llmRS1 : dilepton, llm ED : dilepton,

2/Z

1S

,missTEUED : diphoton + / llγγmLarge ED (ADD) : diphoton & dilepton,

,missTELarge ED (ADD) : monophoton + ,missTELarge ED (ADD) : monojet +

mass862 GeV , 7 TeV [1207.6411]1

=2.0 fbL

mass (|q| = 4e)490 GeV , 7 TeV [1301.5272]1

=4.4 fbL

Scalar resonance mass1.86 TeV , 7 TeV [1210.1718]1

=4.8 fbL

)µµ mass (limit at 398 GeV for L±±H409 GeV , 7 TeV [1210.5070]

1=4.7 fbL

| = 0)τ| = 0.063, |Vµ| = 0.055, |Ve

mass (|V±N245 GeV , 8 TeV [ATLASCONF2013019]1

=5.8 fbL

) = 2 TeV)R

(WmN mass (1.5 TeV , 7 TeV [1203.5420]1

=2.1 fbL

))T

ρ(m) = 1.1 T

(am, Wm) + T

π(m) = T

ρ(m mass (T

ρ920 GeV , 8 TeV [ATLASCONF2013015]1

=13.0 fbL

)W

) = MT

π(m) T

ω/T

ρ(m mass (T

ω/T

ρ850 GeV , 7 TeV [1209.2535]1

=5.0 fbL

= m(l*))Λl* mass (2.2 TeV , 8 TeV [ATLASCONF2012146]1

=13.0 fbL

b* mass (lefthanded coupling)870 GeV , 7 TeV [1301.1583]1

=4.7 fbL

q* mass3.84 TeV , 8 TeV [ATLASCONF2012148]1

=13.0 fbL

q* mass2.46 TeV , 7 TeV [1112.3580]1

=2.1 fbL

)Q

/mν = qQκVLQ mass (charge 1/3, coupling 1.12 TeV , 7 TeV [ATLASCONF2012137]1

=4.6 fbL

T mass (isospin doublet)790 GeV , 8 TeV [ATLASCONF2013018]1

=14.3 fbL

b’ mass720 GeV , 8 TeV [ATLASCONF2013051]1

=14.3 fbL

t’ mass656 GeV , 7 TeV [1210.5468]1

=4.7 fbL

gen. LQ massrd

3534 GeV , 7 TeV [1303.0526]1

=4.7 fbL

gen. LQ massnd

2685 GeV , 7 TeV [1203.3172]1

=1.0 fbL

gen. LQ massst

1660 GeV , 7 TeV [1112.4828]1

=1.0 fbL

W’ mass1.84 TeV , 8 TeV [ATLASCONF2013050]1

=14.3 fbL

W’ mass430 GeV , 7 TeV [1209.6593]1

=4.7 fbL

W’ mass2.55 TeV , 7 TeV [1209.4446]1

=4.7 fbL

Z’ mass1.8 TeV , 8 TeV [ATLASCONF2013052]1

=14.3 fbL

Z’ mass1.4 TeV , 7 TeV [1210.6604]1

=4.7 fbL

Z’ mass2.86 TeV , 8 TeV [ATLASCONF2013017]1

=20 fbL

(C=1)Λ3.3 TeV , 8 TeV [ATLASCONF2013051]1

=14.3 fbL

(constructive int.)Λ13.9 TeV , 7 TeV [1211.1150]1

=5.0 fbL

Λ7.6 TeV , 7 TeV [1210.1718]1

=4.8 fbL

=6)δ (DM4.11 TeV , 7 TeV [1210.1718]1

=4.7 fbL

=6)δ (DM1.5 TeV , 7 TeV [1204.4646]1

=1.0 fbL

=6)δ (DM1.25 TeV , 7 TeV [1111.0080]1

=1.3 fbL

massKK

g2.07 TeV , 7 TeV [1305.2756]1

=4.7 fbL

= 1.0)PlM/kGraviton mass (850 GeV , 8 TeV [ATLASCONF2012150]1

=7.2 fbL

= 0.1)PlM/kGraviton mass (1.23 TeV , 7 TeV [1208.2880]1

=4.7 fbL

= 0.1)PlM/kGraviton mass (2.47 TeV , 8 TeV [ATLASCONF2013017]1

=20 fbL

1 ~ RKKM4.71 TeV , 7 TeV [1209.2535]1

=5.0 fbL

1Compact. scale R1.40 TeV , 7 TeV [1209.0753]1

=4.8 fbL

=3, NLO)δ (HLZ SM4.18 TeV , 7 TeV [1211.1150]1

=4.7 fbL

=2)δ (DM1.93 TeV , 7 TeV [1209.4625]1

=4.6 fbL

=2)δ (DM4.37 TeV , 7 TeV [1210.4491]1

=4.7 fbL

Only a selection of the available mass limits on new states or phenomena shown*

1 = ( 1 20) fbLdt∫ = 7, 8 TeVs

ATLASPreliminary

ATLAS Exotics Searches* 95% CL Lower Limits (Status: May 2013)


Summary and outlook

Huge amount of work has been done by CERN experiments

Antimatter has been created and studied in some detail

The Higgs boson discovered in 2012 so far looks like the Standard Model Higgs

The Standard Model is standing strong – no SUSY, no sign of any exotics either. . .

Some data still to be analysed, and much more data is still to come

Hoping for many fascinating discoveries in the near future!


Web Resources

1. Lancaster Particle Physics Package for A-level students:

http://www.hep.lancs.ac.uk/package/

Some basic stuff - worth a look or two (feedback welcome)

2. Paricle Physics in the UK website, plenty of info and links:

http://hepweb.rl.ac.uk/ppUK/

3. FNAL (Fermi National Accelerator Laboratory), home of the Tevatron:

http://www.fnal.gov/

4. CERN (European Centre for Nuclear Research), home of LEP and LHC:

http://public.web.cern.ch/public/

5. The ultimate resource: Particle Data Group website

http://pdg.lbl.gov

The official reference for all particle data. Many useful review articles, too


Info on Higgs discovery in ATLAS

Web-page with the official Press release:

http://www.atlas.ch/news/2012/latest-results-from-higgs-search.html

Official press release in Georgian:

http://www.atlas.ch/news/2012/HiggsStatementATLAS-Georgian.pdf

Other ATLAS Higgs resources:

http://www.atlas.ch/HiggsResources/


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